Rotary seal

ABSTRACT

A rotary seal is provided which will operate to maintain a seal between relative rotating parts when there is substantial axial movement between the parts by providing a pair of annular members telescopically disposed which will telescope on axial relative movement of the parts. Flexible sealing is provided between the two telescoping parts to maintain a fluid tight arrangement.

United States Patent [191 Place 51 Jan. 29, 1974 ROTARY SEAL [75]Inventor: Bruce S. Place, Warwick, RI.

[73] Assignee: Magnetic Seal Corp., West Barrington, R1.

[22] Filed: Oct. 4, 1971 [21] Appl. No.: 185,935

[52] US. Cl 277/38, 277/43, 277/92 [51] Int. Cl Fl6j 9/00 [58] Field ofSearch 277/38, 86, 41, 80, 91, 88,

[56] References Cited UNITED STATES PATENTS 3,588,127 6/1971 Coleman277/92 2/ 1956 Dickinson 2,736,579 277/81 X 2,890,901 6/1959 Martin277/36 3,050,319 8/1962 Colby 277/41 Primary Examiner-Samuel B. RothbergAttorney, Agent, or FirmHerbert B. Barlow et al.

[ ABSTRACT A rotary seal is provided which will operate to maintain aseal between relative rotating parts when there is substantial axialmovement between the parts by providing a pair of annular memberstelescopically disposed which will telescope on axial relative movementof the parts. Flexible sealing is provided between the two telescopingparts to maintain a fluid tight arrangement.

2 Claims, 3 Drawing Figures ROTARY SEAL BACKGROUND OF THE INVENTION Inthe art of rotary seals, it has been common practice to urge the sealingfaces together by means of a compression spring. If axial movementbetween the housing through which a rotating shaft passes and the shaftoccurs, the face load, that is, the pressure exerted between the sealingfaces will vary as the relative positions change. Since it is common tohave one of the seal faces manufactured of carbon, it becomes obviousthat considerable wear of the carbon will take place as the face load isincreased. Further there are frictional forces involved which tend toprevent rapid movement of the spring loaded member which usuallydrivingly engages the shaft by means of an O-ring that is undercompression, which O-ring must of necessity distort and roll. An exampleof a prior art construction where this action occurs is shown in thePayne US. Pat. No. 2,561,132. If the bias force between the sealingfaces is provided by a magnetic force, a slightly different problemexists and, generally speaking, the amount of movement of the drivingand sealing O-ring is limited as, for example, is disclosed in the ColbyUS. Pat. No. 3,080,170.

SUMMARY OF THE INVENTION It is a primary object of the presentinventionto provide a rotary seal of the magnetic type wherein the sealing partsmay permit relative movement between the rotating and fixed parts of arange in excess of three thirty-seconds of an inch, while at the sametime maintaining a constant face load between the sealing faces. This isaccomplished by providing a structure which may be assembled onto arotating shaft comprising two telescoping members to rotate with theshaft. The first telescoping member or outer sleeve is of annular formand carries a sealing face on one end thereof. It receives within it aninner sleeve part which drivingly engages the shaft. An anti-frictionmeans is provided between the member and sleeve to permit axial movementtherebetween and also to provide a drive between the sleeves. This isdone by providing an axially extending groove in each of the parts andreceiving in that groove a ball. Liquid sealing between these twotelescoping portions is preferably had by means of an annular bellowsconnection, which bellows does not add to or detract from the normalsealing face loads.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectionalview through a fragmentary portion of a housing showing the seal mountedon a shaft;

FIG. 2 is a sectional view taken on lines 22 thereof;

and

FIG. 3 is a sectional view taken on lines 22 showing a modified form.

DESCRIPTION OF THE PREFERRED EMBODIMENT There is shown a shaft having ashoulder 11 thereon which forms a shaft section of reduced diameter 12.The shaft 10 and its reduced section 12 pass through an opening 13 in ahousing 14. Opening 13 is shown as having a counterbore 15 so thateffectively the opening is enlarged, and received in this counterbore 15is a ring 16 which provides a first annular sealing face 17. The ring 16is held within the counterbore 15 by having an outwardly facingcircumferential groove 18 in which is received an O-ring 19. The O-ringis sufficiently compressed so that the ring 16 is sealingly andmechanically held in position.

It will be apparent that the first annular sealing face 17 that has beenassociated with or referred to as being related to the ring 16 may insome instances be provided and associated with a housing such as 14 inother fashions than that illustrated in the drawings, which merely showa preferred method of associating the sealing face with the housing.

Cooperating with the sealing member 16 is a second annular membergenerally designated 20. This annular member is made up of a pair ofsleeves, there being an inner sleeve 21 and an outer sleeve 22. Theinner sleeve 21 is received on the shaft section 12 in a manner toprovide a rotary driving connection therewith. For example, the sleeve21 may be a press fit onto the reduced diameter 12 of the shaft 10 ormay be locked to the shaft section 12 in a variety of other ways as, forexample, through the use of a threaded connection with a nut or othermechanical means which are obvious to those skilled in the art. Toinsure a fluid tight seal between the sleeve 21 and the shaft section12, the sleeve 21 may be provided with a groove 23 in which an O- ring24 is received, which O-ring is compressed into sealing engagementbetween the parts. About the outer surface of the sleeve 21, there isprovided a plurality of axially extending grooves 25. In FIG. 2, threesuch grooves are shown, while in the embodiment of FIG. 3, two suchgrooves are shownv The inner sleeve 21 also is provided with a raisedannular boss section 26, the purpose of which will be presentlyapparent.

Surrounding the inner sleeve 21 is the outer sleeve 22 which effectivelytelescopes therewith. Driving connection between the inner and outersleeve is had by providing a plurality of axially extending grooves 30of the same number as the grooves 25 and received in the grooves 25 and30 is a ball 31. The ball is retained in position by a ring 32 that isreceived on the inner sleeve 21. It will also be apparent that the balls31 serve as an anti-friction means permitting the outer sleeve 22 totelescope relative to the inner sleeve 21. In order to provide a sealbetween the two telescoping parts 21 and 22, a bellows 35 is provided,and this bellows is cemented as at 36 to the raised boss 26 of the innersleeve and at 37 to the outer sleeve 22. It may, of course, be fastenedin a number of other ways known to those skilled in the art but willextend effectively between the end wall 40 of the outer sleeve 22 andthe inner sleeve 21, particularly the raised boss portion 26 thereof.This bellows does not provide any axial force of a sealing nature, thatis, form any closing function and merely serves to provide a seal. Sincepressure will normally be exerted radially inward, the bellows 35 willbe deformed substantially as shown in the drawing.

The outer sleeve 22 may be provided with a carbon ring 42 which has asealing face 43 that engages the sealing face 17 of the ring member 16.The outer sleeve 22 and the ring member 16 are urged together bymagnetic force. To this end one of the parts would be made of amagnetizable material such as that sold under the trade name Alnico" andthe other part have a suffcient ferric content so that a magnetic fluxmay be established therebetween for attraction.

The magnetic attraction between the parts 16 and 22 is the sole forcethat maintains contact between them.

I claim: 1. In a seal between a housing part and a shaft extendingthrough said housing part in which the shaft has axial androtationalmovement relative to the housing part, a first annular member having asealing face associated with said housing part, said face extending in asingle plane normal to the axis of the shaft, a second annular memberhaving a sealing face adapted to engage the first sealing face, saidsecond annular member having an inner sleeve rotationally secured onsaid shaft in fluid tight engagement therewith and an outer sleevehaving two end walls and carrying said second sealing face on one endwall thereof, said outer sleeve being telescopically disposed withrespect to the inner sleeve providing substantially overlapped portions,means including in said overlapped portions at least a pair of axiallyextending grooves in the outer wall of the inner sleeve each having abottom wall and at least a pair of axially extending grooves with abottom wall in the inner wall of the outer sleeve in circumferentialalignment with the grooves in the outer wall with antifriction ballmeans received in said grooves and engaging said bottom walls to allowthe outer sleeve to telescope with respect to the inner sleeve, saidgrooves being of a length greater than the diameter of said ball means,means urging the sealing faces together and maintaining substantiallyconstant pressure between said sealing faces and an expansible fluidtight seal between the other end wall of the outer sleeve and the innersleeve.

2. In a seal as in claim 1 wherein a first annual sealing member isprovided in the housing part, said member carrying the first annularsealing face and wherein said inner sleeve is press fitted onto theshaft.

1. In a seal between a housing part and a shaft extending through saidhousing part in which the shaft has axial and rotational movementrelative to the housing part, a first annular member having a sealingface associated with said housing part, said face extending in a singleplane normal to the axis of the shaft, a second annular member having asealing face adapteD to engage the first sealing face, said secondannular member having an inner sleeve rotationally secured on said shaftin fluid tight engagement therewith and an outer sleeve having two endwalls and carrying said second sealing face on one end wall thereof,said outer sleeve being telescopically disposed with respect to theinner sleeve providing substantially overlapped portions, meansincluding in said overlapped portions at least a pair of axiallyextending grooves in the outer wall of the inner sleeve each having abottom wall and at least a pair of axially extending grooves with abottom wall in the inner wall of the outer sleeve in circumferentialalignment with the grooves in the outer wall with anti-friction ballmeans received in said grooves and engaging said bottom walls to allowthe outer sleeve to telescope with respect to the inner sleeve, saidgrooves being of a length greater than the diameter of said ball means,means urging the sealing faces together and maintaining substantiallyconstant pressure between said sealing faces and an expansible fluidtight seal between the other end wall of the outer sleeve and the innersleeve.
 2. In a seal as in claim 1 wherein a first annual sealing memberis provided in the housing part, said member carrying the first annularsealing face and wherein said inner sleeve is press fitted onto theshaft.